Photo Finish and Timing Resolution Interpreter

Which timing method is official for which event, and the unit the time must be written down in. Every resolution rounds to the next LONGER unit rather than to the nearest, and two of World Athletics’ rules turn an automatic system into a hand timer or into nothing at all.

Last updated 12 Oct 2026

How must this time be recorded?

Technical Rule 19

Timing methodTechnical Rule 19.1 recognises three methods as official — hand timing, fully automatic timing from a photo finish system, and transponder timing, the last for certain events only. The fourth and fifth options are the two mixed cases Rules 19.17 and 19.18 deal with, and they are dealt with very differently.

EventThe three bands the recording rules use. The third covers road races, road race walking and cross country — the events Technical Rules 54 to 57 govern, which is also the only place a transponder system is official.

The raw time in secondsAs the equipment produced it, before any rounding, in seconds. 1577.533 is 26:17.533, which is the figure in Technical Rule 19.23.1’s own worked example. The page uses this only to tell you whether the time is already exact at the required resolution or has to be rounded up.

Recorded to the next longer 0.01 secondExample

A fully automatic 1,577.533 seconds — 26:17.533 — in a 10,000 m

The resolution matrix, with the rule behind every cell

Read from World Athletics’ Technical Rules, Rule 19, in the copy stating “In force from 1 November 2019” with an amendment of 31 January 2020. Two features of the table are worth noticing. Outside the stadium every method collapses to the whole second, so a road result carries no decimals whatever equipment produced it. And the hand-timing row does not coarsen at 10,000 m, because it is already at a tenth — so beyond 10,000 m a hand time and a fully automatic time are recorded to the same resolution, which is the one place in the rules where the two are written down identically.
Method	Track, up to 10,000 m	Track, beyond 10,000 m	Outside the stadium
Fully Automatic Timing	next longer 0.01 s — TR 19.23.1	next longer 0.1 s — TR 19.23.2	next longer whole second — TR 19.23.3
Hand timing	next longer 0.1 s — TR 19.10.1	next longer 0.1 s — TR 19.10.1	next longer whole second — TR 19.10.2
Transponder system	not official — TR 19.1.3	not official — TR 19.1.3	next longer whole second — TR 19.24.5
Automatic at the finish, hand-started	a hand time — TR 19.17	a hand time — TR 19.17	a hand time — TR 19.17
Automatic at the start, not at the finish	not an official time — TR 19.18	not an official time — TR 19.18	not an official time — TR 19.18

Every example the rules print themselves

All six are the rules’ own worked examples, quoted. The last column is the point: in five of the six the rule’s answer differs from rounding to the nearest, and in every one of those five the rule’s answer is the SLOWER time. World Athletics never rounds to the nearest when it writes a time down — it converts to the next longer unit — and it applies the same direction to a wind reading, which is rounded to the next higher tenth so that a tailwind is never understated. The principle is that the athlete is never flattered by the arithmetic.
Raw time	Recorded as	Rule	Nearest would have given
10.11	10.2	TR 19.10.1, hand on the track	10.1
2:09:44.3	2:09:45	TR 19.10.2, hand outside the stadium	2:09:44
26:17.533	26:17.54	TR 19.23.1, automatic up to 10,000 m	26:17.53
59:26.322	59:26.4	TR 19.23.2, automatic beyond 10,000 m	59:26.3
2:09:44.322	2:09:45	TR 19.23.3, automatic outside the stadium	2:09:44
2:09:44.3	2:09:45	TR 19.24.5, transponder	2:09:44

What a photo finish system has to be

From the same read of Rule 19. The image rate is the figure that explains the hundredth: a thousand frames a second resolves a millisecond, so recording to a hundredth throws away an order of magnitude the equipment has, deliberately. Rule 19.2 is the one that settles arguments about photographs: it is the TORSO that has to reach the line, explicitly not the head, neck, arms, legs, hands or feet, so a dipping shoulder counts and an outstretched hand does not.
Requirement	Figure	Rule
Image rate, major competitions	at least 1000 images per second	TR 19.13.1
Image rate, other competitions	at least 100 images per second	TR 19.13.1
Time scale on the image	graduated in 0.01 s	TR 19.13.1
Delay from the gun to the start of timing	constant, and 0.001 s or less	TR 19.13.2
Check before each session	a zero control test	TR 19.19
Cameras	at least two, one from each side	TR 19.20
Alignment marking at the finish	black, confined to the intersection, no more than 20 mm beyond it	TR 19.14
Where the time is taken	the torso reaching the vertical plane of the nearer edge of the finish line	TR 19.2
If the photo finish time is obviously inaccurate	the back-up timekeepers’ times become official	TR 19.22

Three official methods, five resolutions, and never to the nearest

This page is about athletics — track and field, and road running — whose competition rules, technical rules and scoring tables are published by World Athletics, the body that was the IAAF until 2019. Where a figure below belongs to a particular edition of those rules, the edition is named beside it, because World Athletics revises them and a number quoted without its edition will be wrong for somebody.

World Athletics Technical Rule 19.1 recognises exactly three methods of timekeeping as official: hand timing, fully automatic timing from a photo finish system, and timing from a transponder system — the last “official for competitions held under Rules 54, 55, 56 and 57 of the Technical Rules only”, which is to say the events not held completely inside the stadium. A chip time is therefore not an official time for a 5,000 m on the track, however good the equipment is.

The single most useful thing on this page is that no resolution in the rules is a rounding. Every one of them converts the time to the next LONGER unit, unless it already lands exactly on that unit. Rule 19.10.1 records a hand time on the track “to the next longer 0.1 second” and prints its own example: “10.11 shall be recorded as 10.2”. Read against instinct, that is a tenth added to a time which is nearer to 10.1. Rule 19.23.1 records a fully automatic time up to 10,000 m “to the next longer 0.01 second”, with “26:17.533” becoming 26:17.54. The direction is consistent across the rulebook — it is the same direction World Athletics applies to a wind reading, which is rounded up so a tailwind is never understated — and the principle is that the arithmetic never flatters the athlete.

The resolutions themselves are not about the equipment. A photo finish system at a major competition has to compose its image from “at least 1000 images per second” under Rule 19.13.1, which resolves a millisecond, and its start delay has to be “constant and equal to or less than 0.001 second” under 19.13.2, confirmed by a zero control test before every session under 19.19. The same machine reading the same image has its answer written down to a hundredth for a 10,000 m, to a tenth for a 20,000 m, and to a whole second for a marathon. What changes is what the result sheet is allowed to claim, and on the road the limit is the course: a certified road course is measured along the shortest possible route with a 0.1% short course prevention factor built in, so its length is good to about a metre in a thousand and a hundredth of a second on a two-hour time would be precision the distance does not have.

Two rules deal with the mixed cases and they go in opposite directions, which is the part people get wrong. Rule 19.17 says a system that is automatic at the finish but started by hand produces hand times — official, but recorded to a tenth on the track. Rule 19.18 says a system automatic at the start but not at the finish produces neither a hand time nor an automatic one and “cannot be used for official times” at all. The asymmetry follows from where the time is read: Rule 19.2 takes it at the moment the athlete’s torso — explicitly not the head, neck, arms, legs, hands or feet — reaches the vertical plane of the nearer edge of the finish line, and no human eye resolves that to a hundredth. The finish is the hard half.

An honest note about which edition this is. World Athletics publishes the Competition Rules and the Technical Rules as one combined PDF, and the three copies of it that returned readable text at all — the current official one, last modified 1 July 2026; a member federation’s copy of the edition in force from 1 November 2019; and a school board’s copy of the edition effective 1 January 2022 — return between 100,000 and 123,000 characters each and then stop. The current one stops inside the Technical Rules at about Rule 5, and a fourth copy, an official asset file, returned no readable text whatever. So the rule text quoted here was read in an earlier edition, and where a figure could also be found in World Athletics Council’s own March 2025 amendment table it is taken from there instead, because that table prints the current and the amended wording side by side. Check a rule number against the edition your competition is run under.

This page rules on which method is official and how a time must be written down. It does not convert between methods, and the distinction is worth keeping clean: a hand time recorded to a tenth under Rule 19.10.1 is a legitimate official time, not a defective automatic one, and nothing in Rule 19 turns one into the other. Where somebody does publish a conversion — World Masters Athletics, for ranking an old hand time against a modern automatic one — the hand timing to electronic conversion calculator has the figures, the order they are applied in, and the printed disagreement about whether they mean anything. For the other way a legitimate time can fail to count, the wind reading and altitude legality interpreter has Competition Rule 31 and the rounding rule that makes a raw +2.03 illegal — the same round-against-the-athlete direction, applied to the wind gauge.

Frequently asked questions

How precisely is a track time recorded?

To the next longer hundredth of a second for a fully automatic time in a race up to and including 10,000 m, to the next longer tenth beyond that, and to the next longer tenth for any hand time on the track. World Athletics Technical Rules 19.23.1, 19.23.2 and 19.10.1. None of them is a rounding to the nearest.

Why is 10.11 recorded as 10.2 rather than 10.1?

Because Technical Rule 19.10.1 converts a hand time “to the next longer 0.1 second” unless it is already an exact tenth, and that is the rule’s own printed example. It is not rounding; it is always upward. The principle runs through the rulebook: the arithmetic never flatters the athlete.

Why do marathon times have no decimals?

Because every method is recorded to the next longer whole second outside the stadium — Rule 19.23.3 for fully automatic timing, 19.10.2 for hand timing and 19.24.5 for a transponder system. The rules print the same example three times over: 2:09:44.322 or 2:09:44.3 is recorded as 2:09:45.

Is a chip time an official time?

Only outside the stadium. Technical Rule 19.1.3 makes transponder timing official for competitions held under Technical Rules 54 to 57 only — road races, road race walking and cross country — subject to six conditions in Rule 19.24, and the official time runs from the gun to the athlete reaching the finish line rather than chip to chip. For a track race it is not official at all.

What happens if the gun is not wired to the timing system?

The times become hand times. Technical Rule 19.17 says a system that operates automatically at the finish but not at the start produces hand times, provided the start was accurate enough — so they are official, and they are recorded to a tenth on the track. The opposite case is worse: Rule 19.18 says a system automatic at the start but not at the finish “cannot be used for official times”.

Which part of the body stops the clock?

The torso. Technical Rule 19.2 takes the time at the moment any part of the athlete’s body reaches the vertical plane of the nearer edge of the finish line, and specifies that this means the torso as distinct from the head, neck, arms, legs, hands or feet. A dipping shoulder counts; an outstretched hand does not.

Related calculators

References

World Athletics. Book C — C2.1 Technical Rules, the copy hosted by the Latvian Athletics Association (athletics.lv), which states “In force from 1 November 2019” and an amendment of 31 January 2020 (read 15 Oct 2026; 116,671 characters of readable text, ending inside Rule 20.4, so Rules 22 onward are not in it). Rule 19.1, “Three methods of timekeeping shall be recognised as official” — Hand Timing, Fully Automatic Timing from a Photo Finish System, and Transponder timing, the last “official for competitions held under Rules 54, 55, 56 and 57 of the Technical Rules only”. Rule 19.10.1, a hand time on the track “shall be converted and recorded to the next longer 0.1 second” unless it is an exact tenth, “e.g. 10.11 shall be recorded as 10.2”; Rule 19.10.2, for races partly or entirely outside the stadium, “to the next longer whole second”, “e.g. 2:09:44.3 shall be recorded as 2:09:45”. Rule 19.23.1, a fully automatic time up to and including 10,000m to the next longer 0.01 second, “26:17.533” recorded as 26:17.54; 19.23.2, a track race longer than 10,000m to the next longer 0.1 second, “59:26.322” as 59:26.4; 19.23.3, outside the stadium to the next longer whole second, “2:09:44.322” as 2:09:45. Rule 19.24.5, a transponder time to the next longer whole second. Rule 19.13.1, a composite image of “at least 1000 images per second” at major competitions and “at least 100 images per second” elsewhere, on a time scale graduated in 0.01 s; 19.13.2, the delay from the gun to the start of timing “constant and equal to or less than 0.001 second”. Rule 19.17, a system automatic at the finish but not the start produces HAND times; Rule 19.18, one automatic at the start but not the finish produces neither and “cannot be used for official times”. Rule 19.19, a zero control test before each session; 19.20, “there should be at least two photo finish cameras in action, one from each side”; 19.22, photo finish times are official unless judged obviously inaccurate, when the back-up timekeepers’ times become official.
World Athletics. Book C — C1.1 & C2.1: Competition Rules & Technical Rules, the single combined PDF linked from worldathletics.org/about-iaaf/documents/book-of-rules, listed there as last modified 1 July 2026 (fetched 15 Oct 2026). CITED FOR WHAT IT COULD NOT DELIVER, because that is load-bearing: the fetch returns 123,065 characters of readable text and stops inside the Technical Rules at about Rule 5, so Technical Rules 19, 22, 23, 24 and 32 to 34 are NOT in the readable text of the current edition. Its amendment table came through, with effective dates running from 17 December 2020 to 1 July 2026. The page lists C1.1 and C2.1 as one document, so there is no shorter Technical Rules file to fetch instead.
World Athletics. “Book of Rules” index page, worldathletics.org/about-iaaf/documents/book-of-rules (read 15 Oct 2026). The authoritative list of what the rule book currently consists of, and the source of the document codes used on these pages. It lists “C1.1 & C2.1 – Competition Rules & Technical Rules” as a single combined document, last modified 1 July 2026, with no separate Technical Rules file; “C2.1A – Athletic Shoe Regulations (effective from 20 April 2026)”, last modified 19 March 2026, the only entry in the whole list whose effective date is printed in its own title; “C2.1B Mechanical Aids Regulations”, last modified 10 March 2022; and “C1.6 Label Road Race Regulations”, last modified 3 August 2026. Cited because the codes and the dates on these pages are taken from it rather than from a secondary account, and because it establishes that there is no shorter Technical Rules download to try.
Cundy, Dave, and Hugh Jones. The Measurement of Road Race Courses, second edition 2004, updated 2008, published jointly by the IAAF and the Association of International Marathons and Distance Races; read 15 Oct 2026 from the copy on media.aws.iaaf.org (roughly 70,000 to 80,000 characters, the data sheets cut off at the end). Cited here for two statements only: the then-current IAAF Rule 240.3, “In events on roads the course shall be measured along the shortest possible route that an athlete could follow” with “the uncertainty in the measurement shall not exceed 0.1% (i.e. 42m for the Marathon)”; and the short course prevention factor, “For bicycle measurements this factor should be 0.1% which means that each km on the course will have a ‘measured length’ of 1001m.” The full entry, with the method and both worked examples, is on the measurement page.